Hey guys. Ive been reading all the great posts and am starting to plan
a rewire of a house we just bought (from old knob and tube)
I've helped plan/install a new wire up before so have a pretty good
idea of what needs to happen on the electrical side of things.
Questions I havent seen to much of on this group.
Star vs sequential wiring topology... All the new wiring we ran in the
other house was sequential so I assume its the cheapest/most efficient
way to go for most situations. For an old plaster/lathe house though
with only access from above it seems that the star topology is the way
to go... anything I should watch out for using this method (Running
all the wires to the attic and dropping each switch/receptacle from
Running pipe in conduit... Ive got a great 4 inch pvc pipe from the
basement to the attic that I can drop the lines down. What is the code
as to how much wire per inch you can jam in to PVC... Is PVC as conduit
legal? Anything else I should worry about?
Any one who has done this who wants to add their two cents... fire
FYI: this house is in Vancouver, Canada. Its a bungalo with a finished
basement and good attic access.
Thanks a bunch
Good luck with your project. I've been working on a rewire of my house
for a while now and it's quite a job.
I think the only major issue with a star topology would be trying to
stuff too many wires in a junction box. They add up quickly. I'm sure
it's manageable but just something to keep in mind. There are tables in
books and on the web to help figure it out.
If you have a local electrical inspector then this is something you'll
definitely need to check with them about. Based on what I know, if it's
electrical PVC then it should definitely be OK to use. Plumbing PVC
would be questionable. It might be useful as a sleeve for other, smaller
In the US if you run more than I believe 4 current carrying wires in a
conduit then rules come into play that end up reducing the current
carrying capacity of the wires. Multiple NM cables in conduit over
distances also seems to be a question mark since they're not really
designed to be run in conduit in the first place.
There's a link on this excellent site with information on basic conduit
It's for the US NEC but should give you a starting point. They also have
message board for the CEC.
If you find you have to limit the number of cables you can run then you
might want to read up on Edison or shared neutral circuits if you're not
familiar with them. You probably are since I believe they're commonly
used for kitchens in Canada. They would allow you to get 2 120V circuits
with a single 3 conductor + ground cable. These could be used as the
trunk lines to the attic.
I've rewired 2 old houses using the 'star' approach. On the last one I
split the 2nd floor into 4 zones and used 12 gauge wire (on 20 amp
circuits). One zone was 2 bedrooms, one zone was the other 2 bedrooms,
one was the bathroon (only one but very large), and one zone was all
the stair and hallway lighting and receptacles. I had to use the star
approach because it was all lathe and plaster knob/tube. The knob/tube
removeal leaves a lot of handy holes to run your wire thru but of
course back then there were only 1 or 2 outlets per room.
I created all the runs in one bedroom, brought them to one large
workbox, then ran a line from two bedroom workboxes to a central
workbox, into which I also brought the hot lead. You don't want to
bring any more wires into a box than it can hold and with which you can
work. Five 12 gauge wires require a pretty big wire nut.
Anywho the concept I used (code ?) was to create my runs to the lights
and outlets, bring them to some connvenient 'collection point', then
connect the collection points. One thing to consider, if you're up in
the attic and the attic has usable space, is to do all this below the
level of the floor. This is much more difficult of course, because you
have to drill holes but there will also be a lot of nice, dime-sized
holes already there from the knob and tube.
'Star' can also be used in the basement to do the first floor of a
2-story house, for example), the star being in the basement. If your
basement weren't finished this IMO woul dbe the way to go, from below.
The only thing I don't have an opinion on is the conduit question.
First house I did I had a place I could tack the wires up individually.
Last house I got around the conduit problem by finding a place I could
run a 6 gauge wire to a branch circuit box in the attic. Had an
electrician do that just to make sure it was done correctly, as it
required a new breaker in the main box. Having a branch box in the
attic makes life much easier than running all those 12 (or 14) gauge
wires from the attic to the breaker box in the basement.
Thanks guys for the quick response. Good site suggestion Doug.
Has anyone seen a box that allows for multiple connections with out
wire nuts? Something similar to a bus bar on a breaker panel (but
without the fuses)
I've not seen anything prebuilt but there are lots of terminal
strips/blocks out there:
I'm not sure how to actually put them to use safely.
I've been using some Wago Wall-Nuts lately and they're helpful in certain
situations. They're push-in wire connectors that come in various port
configurations allowing up to 8 wires to be connected together on a very
small buss bar without twisting:
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.